The Vehicle Navigation System with a Rotating IMU

In the recent decades, the integration of a MEMS-based (Micro-Electro Mechanical Systems) Inertial Measuring Unit (IMU) with a GNSS receiver-chip has become commonly used navigation techniques by virtue of their advantages such as their complementary characteristics overcome each other's shortcomings, and small sized, light weight, with low power consumption, and have extremely low cost. However, when there is no external auxiliary information, the inertial navigation error based on low-cost MEMS IMU will quickly accumulate over time. Reducing inertial navigation error has great potential in many applications. Conventional ground vehicles are restricted by Non-Holonomic Constraint (NHC), during the outage of GPS. Although the navigation performance of the inertial system with only NHC as the motion constraint is improved, the observability of the system is still poor due to the lack of forward speed constraint. According to MEMS IMU, an innovative method is proposed to improve the observability of the inertial navigation system through continuous rotation of a single MEMS IMU around a certain axis, during the outage of GPS. In this paper, although the azimuth error is still unobservable, both theoretical analysis and the results indicate that the system observability is improved by rotating IMU. The enhanced estimability of the gyro bias in the vertical direction can effectively mitigate the azimuth error accumulation.